1. Field of the Invention
This invention pertains to folder pockets, more specifically to a slit-opening pocket for heavy or bulky flat objects such as pad stiffeners, packs of paper, and computer diskettes, in a die cut sheet liner for a folder or book cover.
2. Description of the Prior Art
The prior art is replete with patents for a book sheet having a very narrow long slot hereinafter called "slit", pocket opening for insertion of flat objects.
U.S. Pat. No. 2,226,976 patented Dec. 31, 1940 by S. T. Leaming describes a sheet having pairs of upward diverging slits. The outer ends of the slits are spaced from the adjacent edges of the sheet, the lower ends of the slits terminate short of convergency. The outer ends of the slits are enlarged to form entrance openings. The bottom edge of a card that is inserted into a pair of slits first enters the entrance openings and then moves down in the slits until it is stopped by the lower end termination of the slits.
U.S. Pat. No. 4,991,767 patented Feb. 12, 1991 by J. R. Wyant describes a paperboard blank having a transparent plastic overlay. The blank is folded to form a first panel and a second panel, the front of the second panel being glued to the back of the first panel. The first panel has square holes shaped to frame photographs, the overlay forming windows over the holes. The second blank has slits for receiving photographs between the first and second panels behind the windows.
U.S. Pat. No. 4,571,867 patented Feb. 25, 1986 by M. E. Williams describes a sheet having pairs of upward diverging slits. The outer ends of the slits are spaced from the adjacent edges of the sheet and are the entrance openings for pockets. The lower ends of the slits terminate short of convergency. The bottom edge of card that is inserted into a pair of slits first enters the entrance openings and then moves down until it is stopped by the lower end termination of the slits. A pinch crease of contracting material of the sheet is formed between and spaced from the near terminal ends of each pair of downwardly converging slits to pull the sections of sheet material that contains the slits in order to cause the legs of sheet material formed between the slits to twist and partially open the slits for easier insertion of cards into the slits.
U.S. Pat. No. 5,199,743 patented Apr. 6, 1993 by A. B. Rosinski describes a sheet die cut and folded to form two similar side by side pockets. The sheet is folded on a line into two panels, which we shall call panel A and panel B, which are glued together along a strip that extends normal to the fold line and is at the center of each panel. One pocket is formed by a slot in panel B that extends from the glued strip to the lateral edge of panel B. The pocket can bulge up from the glued surface at a flex line (line 60, FIG. 1) along the glued strip. The other pocket is formed by a slot in panel B that extends from the glued strip to the other lateral edge of panel B, and can bulge up from the glued surface at a flex line along the glued strip. A tab extends from each lateral edge of panel B and folds along the lateral edge. The tab is folded so that it can be glued to panel A between panel A and B when panel B is folded against panel A and is also glued to panel A.
In FIG. 1 die cut sheet 26 of PRIOR ART folder 20 folds on fold line 28 forming panels 22 and 24. Slits 30 and 32 which are transverse to fold line 28 receive cardboard back 36 of a pad, or other papers. Bottom edge 40 of the cardboard passes behind section 42 of panel 22 and inserts into oblique slits 44, 46.
Transverse slits 30, 32 and 44 do not go to the fold line. Slit ends 52, 54, 56 and 58 are spaced from fold lines. The slits or narrow slots have small radius ends or V-shaped ends which tend to rip 48 at ends 52, 54 and 56 from force of forward expansion of the pocket by papers in the pocket, by wear by the papers at the ends of the slits, and by fatigue of the ends of the slit. Slit 46 has large-radius circular punched out ends 58 which lessens ripping from stretching or fatigue.